Avian diseases最新文献

Infectious bronchitis virus (IBV) is a highly contagious disease of major concern to the commercial poultry industry because it significantly affects egg production. The predominant IBV strains vary according to region. The GI-11 lineage is predominantly identified in countries within South America, notably in countries such as Brazil and Uruguay, but it has not been detected in other regions, including South Korea. In this study, using next-generation sequencing, we identified the IBV with a spike gene of the GI-11 lineage in a native chicken farm sample collected in South Korea in 2011. Recombination analysis revealed that the spike region of the isolated virus bears high similarity to the GI-11 lineage, whereas the nonspike regions show high similarity to the GI-19 lineage that is predominantly found in South Korea, which suggests the occurrence of recombination. The poultry product trade and related human activities are suspected to be sources of intercontinental viral spread. Therefore, to prevent the introduction of new viruses, it is imperative to enhance and enforce quarantine measures.

A mortality of young pheasants (Phasianus colchicus) with necrotizing hepatitis was reported on a farm in California. Ultrastructurally, nonenveloped, icosahedral, 24 nm (SD = 2 nm) viral particles were detected in the liver. Whole-genome sequencing detected a chaphamaparvovirus from the liver sharing 94.4% nucleotide identity with Phasianus chaphamaparvovirus-1 (PhChPV-1). This is the first report of PhChPV-1 causing necrotizing hepatitis in pheasants in the United States. Since these pheasants are used for hunting activities, the spreading of PhChPV-1 into the wild should be taken into consideration.

Infectious bronchitis is an acute, highly contagious avian disease affecting chickens worldwide and is associated with respiratory signs, nephritis, and egg production disorders, causing major economic problems in the poultry industry. Limited information is available on the infectious bronchitis virus (IBV) strains circulating in Indonesia. This study sequenced the whole genome of six IBVs isolated from various regions in Indonesia during 2021-22. Phylogenetic analysis of the S1 subunit (S1) of the spike glycoprotein (S) coding sequences classified these strains within the GI-19 lineage, with no evidence of recombination in the S1 coding sequences. Full-genome analysis revealed evidence of recombination, but potential progenitors could not be identified due to the lack of closely related sequences in public databases. The closest genetic relatives to these Indonesian strains are IBVs from Malaysia and Thailand, likely due to geographic proximity. To our knowledge, this is the first report of whole-genome sequences of IBV strains isolated in Indonesia. These findings contribute to a deeper understanding of the epidemiology of current IBV strains circulating in Southeast Asia.

Elevated mortality and culling were reported from 7-day-old broilers in the U.K. Chicks in two affected houses showed clinical signs of weakness and lameness with wet litter. Necropsy findings from dead and culled lame chicks included minimally widened tibiotarsal growth plates, superficial erosions on the gizzard koilin layer, and mildly congested kidneys in several birds. Antibiotic treatment and vitamin D₃ supplementation were commenced, and the feed was replaced. The mortality and culling rate remained elevated for several more days but were confined to the two affected houses. Bacteriologic examination yielded no significant findings. Undersized birds were examined by necropsy 4 days later to investigate deteriorating uniformity. Grossly widened tibiotarsal growth plates were apparent, with suspected osteomyelitis or thickened proventriculi in several birds. Histologic examination of tibiotarsal growth plates revealed mild osteodystrophy and tibial dyschondroplasia. Mineralization or calcium deposits or both were identified histologically and confirmed histochemically within the koilin cuticle of the gizzard, the kidneys, and the proventriculus. No significant findings were noted in the brain, tendon, skeletal muscle, heart, and peripheral nerves. Feed analysis from the initial starter ration revealed that calcium and phosphorous levels were, respectively, approximately three and four times in excess of target levels, with a reduced calcium:phosphorous ratio. The culling rate for lameness and being undersized remained elevated for the duration of the crop, with high overall mortalities of approximately 15%. This is an unusual case of very early lameness due to rickets with metastatic visceral mineralization. The staining characteristics of the mineral deposits also provide interesting clues regarding their chemical nature.

Testicular cysts in poultry are pathologic conditions with significant implications for reproductive health and flock performance. This study investigated the clinical, molecular, and pathologic impacts of chronic sodium toxicity and its interplay with infectious agents in broiler chickens. In a flock of 22,600 Ross broiler chickens, a severe mortality rate (88.3%) was reported after showing signs of disease such as reduced feed intake, diarrhea, and lethargy. At necropsy, hydropericardium and testicular cysts, with no evidence of ascites, were observed. Severe intestinal necrosis, renal lesions characteristic of membranoproliferative glomerulonephritis, and in the testes, atrophy with no epithelial germ cells or seminiferous tubules were observed during histopathologic examination. Analysis of the feed revealed high levels of sodium in the feed (0.64% in the starter feed and 0.65% in the finisher feed). PCR assays detected adenovirus DNA, with positive results on day 15 and negative results on day 35, while bacterial cultures identified Escherichia coli exhibiting multidrug resistance. Symptoms and mortality did not improve with antibiotic treatment. Although adenoviral DNA was detected, the histopathologic findings supported sodium toxicity as the primary causative factor. Histopathologic examination, alongside PCR assays, is crucial for achieving a comprehensive and accurate understanding of the underlying causes in such cases. These findings show that there can be an interaction between an imbalanced diet and pathogens in broilers and thus the need for accurate feed formulation and diagnostic approaches to manage multiple causes of disorders in poultry production systems.

Since 2020, Streptococcus gallolyticus infection has emerged as one of the leading causes of disease in commercial turkey poults, causing fatal bacterial sepsis without any prior clinical signs except in unusual cases involving central nervous system signs. In this study, eight S. gallolyticus strains-S. gallolyticus subsp. pasteurianus (n = 7) and S. gallolyticus subsp. gallolyticus (n = 1)-were used in a turkey embryo lethality assay that were isolated from outbreaks involving commercial poults in the U.S. Midwest. API 20 STREP V8.0 and API RAPID ID 32 STREP V4.0 were used to identify these S. gallolyticus strains to subspecies level and obtain biochemical profile codes. Whole-genome sequencing revealed eight genetically distinct strains with more than 1283 single-nucleotide polymorphism differences to each other. Additionally, three of these strains contained a potential virulence factor similar to Acb protein, a putative collagen adhesin that promotes high-affinity binding to host-cell-immobilized collagen, suggesting increased advantage for intestinal tissue colonization and bloodstream translocation. Each strain was inoculated at a high (10⁶ CFU/ml) and low dose (10³ CFU/ml) through the air cell of eggs obtained from Nicholas breeding line into the allantoic cavity on day 15 of embryogenesis. Eggs were candled daily for 7 days to determine embryo mortality, thus assessing virulence potential of the strains. The cumulative embryo mortality was highest in the neurological S. gallolyticus subsp. pasteurianus strain in both high (10⁶ CFU/ml) and low (10³ CFU/ml) doses and S. gallolyticus subsp. pasteurianus strain 4 in the high dose (10⁶ CFU/ml). Most embryos that died were inoculated with the high dose of any strain on one day postinoculation. Dead embryos infected with the high dose on days 1 and 2 postinoculation showed generalized superficial and internal petechial hemorrhages and congestion of organs, as well as aggregates of Gram-positive coccoid bacteria in blood vessels and organs, consistent with bacterial sepsis. Only one of the three strains containing the Acb-like protein, the neurological S. gallolyticus subsp. pasteurianus strain, caused increased mortality, suggesting that Acb alone is not responsible for enhanced virulence in this embryo model. Rather, it is possible that additional novel virulence factors, such as L-arabinose metabolism discovered in the neurological S. gallolyticus subsp. pasteurianus strain, may enhance virulence fitness.

Pastured poultry farms offer a unique model for investigating microbial ecology in less controlled environments, presenting challenges and opportunities for food safety management. This study aims to identify the key factors that influence Escherichia coli levels with two complementary modeling approaches: a linear mixed-effect model (LMM) and a random forest (RF) model. Data were collected from 11 pastured poultry farms in the southeastern United States from 2014 to 2017. Five sample types were analyzed: soil (n = 812), feces (n = 817), ceca (n = 206), postprocessing whole carcass rinse (WCR-P; n = 235), and final product whole carcass rinse (WCR-F; n = 230). Two different sets of predictor variables were used separately: 1) 32 farming practices and 26 physicochemical properties and 2) 80 meteorological factors. The model performance was compared with the randomized mean squared error (RMSE) with a test dataset. LMM was not used for meteorological factors because of the multicollinearity. Significant differences (α = 0.05) in E. coli levels were observed between all sample types, with feces samples showing the highest level. Compared to LMMs, RF models generally showed higher predictive accuracy (lower RMSE) on the test dataset. For soil samples, higher pH and sodium levels were linked to higher E. coli levels. The same trend with pH was observed in fecal samples. WCR-P samples showed that the organic acid treatment in the rinse water led to lower E. coli levels than other treatments. In WCR-F samples, longer storage time led to lower E. coli levels. Meteorological factors showed a weaker relationship with E. coli levels compared to farming practices and physicochemical properties, but in soil samples, mild and stable temperature played an important role in E. coli survival. This study can help stakeholders develop data-driven management strategies targeting key factors to aid in the reduction of food safety and animal health risk.

Necrotic enteritis (NE) and coccidiosis continue to be diagnosed in poultry in Canada. Since 2013, the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) has been collecting data on antimicrobial use (AMU) and antimicrobial resistance (AMR) in broiler chicken and turkey flocks, with layer flocks added to surveillance in 2021. This study describes enteric disease control strategies utilized in poultry production from 2018 to 2023, based on farm data reported to CIPARS. In broiler chickens, 85% (51.7 mg/kg broiler chicken biomass) of the total quantity of medically important antimicrobials was used for NE control, compared to 51% (28.1 mg/kg turkey biomass) in turkeys and 74% (16 mg/kg layer biomass) in layers. Since 2019, antimicrobial classes used for NE control have decreased following the voluntary elimination of preventive use of macrolides, penicillins, and streptogramins. Bacitracin remained the most frequently used antimicrobial for NE control across all poultry. For coccidiosis control, ionophores were used more frequently than chemical coccidiostats, with a 2.5:1 ratio in broiler chickens (ionophores: 2892.9 kg; chemical coccidiostats: 1126.6 kg) and a 2.4:1 ratio in turkeys (ionophores: 1840.2 kg; chemical coccidiostats: 749.9 kg). Layer flocks used exclusively monensin (39.3 kg) and amprolium (31.6 kg). Over the surveillance time frame, the diversity of coccidiostats used in broiler chickens and turkeys remained stable. Shuttle/dual-control programs (58%) were commonly used in broiler chickens, whereas continuous/straight programs (51%) were predominant in turkeys. Notably, alternative disease control strategies such as vaccination are emerging or continuing. Clostridium perfringens vaccine was used in 1% of broiler chickens, and coccidiosis vaccines were administered in 13% of broiler chicken flocks, 16% of turkey flocks, and 29% of layer flocks. These nonantimicrobial alternatives may reduce the reliance on AMU. Despite shifts in AMU practices, mortality and enteric disease diagnoses remained stable. The findings highlight the importance of preserving antimicrobial efficacy, including coccidiostats, for gut health. Ongoing surveillance is crucial for monitoring trends in disease control strategies and assessing their impact on poultry health and production.

Infectious bronchitis (IB) is a major viral disease that causes substantial economic losses in the global poultry industry. Despite the implementation of extensive vaccination programs, it remains a persistent threat. Monitoring the antibody response against infectious bronchitis virus (IBV) is essential for studies focused on vaccine development, as well as for evaluating the effectiveness and proper administration of vaccines in poultry flocks. In this study we developed and optimized an indirect enzyme-linked immunosorbent assay (IB-ELISA) for the detection of IBV-specific antibodies. The use of purified virus, obtained through sucrose density gradient centrifugation, was critical for minimizing nonspecific background reactivity. A panel of anti-sera and tracheobronchial lavage samples from IBV-infected and inactivated-vaccine-immunized chickens was tested. The IB-ELISA demonstrated 100% sensitivity and specificity when compared with a commercial IBV ELISA kit used as the gold standard. The assay reliably detected IBV-specific IgG antibodies in both serum and tracheobronchial lavage samples, with positive responses observed as early as 7 days postinfection and 21 days postvaccination, respectively. Although the IB-ELISA could not differentiate between IBV serotypes because of cross-reactivity, it effectively identified antibodies against multiple strains. These findings indicate that the IB-ELISA is a valuable tool for assessing the effectiveness of vaccination programs and for studies requiring the evaluation of both mucosal and systemic IgG responses, including those involving experimental vaccines.

Vaccination with a recombinant Newcastle disease virus (NDV) LaSota (LS) strain expressing Arkansas (Ark) -type infectious bronchitis virus (IBV) spike ectodomain (Se) protein and granulocyte-macrophage colony-stimulating factor (GMCSF) (rLS/ArkSe.GMCSF, where rLS stands for recombinant LS) was evaluated in chickens of commercial origin with NDV and IBV maternally derived antibodies (MDAs). Chickens were vaccinated ocularly with rLS/ArkSe.GMCSF at either 2, 8, 15, or 30 days of age (DOA). Control chickens were vaccinated with the rLS virus (not expressing IBV SE or GMCSF) on the same days. Specific-pathogen-free (SPF) chickens also were vaccinated with either virus at 2 days old. The results showed detection of NDV RNA in lacrimal fluids of vaccinated chickens, indicating successful replication of the recombinant virus at periocular mucosal sites. IBV IgA in lacrimal fluids and serum IBV antibodies were determined by ELISA using recombinant IBV Ark S1-protein-coated plates. Vaccination at 2 DOA with rLS/ArkSe.GMCSF in chickens with MDAs elicited an IBV IgA response in lacrimal fluids. Chickens with MDAs vaccinated with rLS/ArkSe.GMCSF at 8 days old showed IgA levels in lacrimal fluids not differing significantly from levels achieved upon vaccination at 2 DOA. Vaccination at 30 days old did not result in increased IBV IgA levels in tear fluids of birds with MDAs compared to unvaccinated birds with MDAs. Vaccination with rLS/ArkSe.GMCSF of chickens with MDAs resulted in limited IBV and NDV serum antibody responses. We conclude that vaccination with rLS/ArkSe.GMCSF induces IBV IgA at periocular mucosae but limited serum antibody responses in chickens with NDV MDAs.